Actually some one already did that:
https://sites.google.com/site/mytools4000/home/allow-block-multiple-programs-through-windows-7-firewall/

It would help a lot of people if someone could add to that code so that the user specifies a folder and the batch file creates blocking inbound/outbound rules for every .exe and .dll including every...

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etc. etc.

Tried all of that....didn't do anything...no rules were added.

EDIT:

Problem is: when you run this batch file as Admin

it asks whether you want to block Windows/System32 and all its subfolders---NOT EXACTLY WHAT MOST EVERYONE WOULD DESIRE !